OpenColorIO ("OCIO") is an open source system for managing color in film production pipelines. It was originally created for internal use at Sony Pictures Imageworks, who then released it publicly in July 2010. It now includes an After Effects plug-in that I contributed.
The main advantage of OpenColorIO is that it will function identically across all programs that support it. So if you want to make sure that your color transformations in After Effects match those in Nuke (now shipping with OCIO), this is a way to do it.
Of course, like any open source project, the plug-in is free. Anyone is free to download the code, build it themselves, or contribute a change. Here I've got pre-built versions for you, which I'll try to keep up to date with the evolving OCIO library. A PDF manual is also included.
Plug-in version: 1.0.9v2
Date: 6 February 2017
Mac | Win